Conventional internal combustion engines may include a fuel injection system for directly injecting fuel into the combustion chambers of the internal combustion engine. The fuel injection control includes several strategies. One such strategy is a small quantities adjustment (SQA) strategy, namely a strategy for compensating small fuel injections, such as for example pilot injections. The SQA-strategy may be based on a learning phase and a correction phase. The duration of the known learning phase, however, is not deterministic and the time to reach a learning convergence (i.e. to satisfy the above disclosed condition) may be long and indefinite, In order to comply with specific regulation requirements related to injection fuel quantity and energizing time monitoring, a need exists for an improved SQA strategy that allows a faster and more accurate learning phase thereof.
Accordingly, it is desirable to provide an improved small quantity adjustment strategy allowing a fast learning phase so that the fuel injectors can perform more accurate fuel injections also during the normal operation of the internal combustion engine.